Uniroyal RainSport 3 is a summer tyre made in total of 110 sizes, ranging from R14 to R14 - this particular dimension is R19, which means it fits to a 19 inch/482.6mm diameter wheel. 255/45 R19 is 70mm wider than the narrowest dimension (185) and 20mm narrower than the widest one (275). This tyre profile of 45 means the sidewall height of the tyre is 45% of the tyre width (255mm), which results in 114.75mm sidewall height. In 255/45 R19, there is only one possible speed index for Uniroyal RainSport 3 - "Y", which is good for speeds up to 300 km/h.